Conventional semiconductor process chambers, for example, such as Rapid Thermal Processing (RTP) chambers, typically utilize a substrate support having one or more rings (e.g. an edge ring) disposed atop the substrate support and configured to secure the substrate in a desired position during processing. However, the inventors have observed that conventionally used edge rings may have different thermal properties (e.g. different heating and cooling rates) as compared to the substrate support, thereby causing temperature non-uniformities proximate the edge of the substrate, thus causing an undesirable non-uniform processing of the substrate. In addition, the edge ring may be heated to a higher temperature than the substrate support during processing due to the configuration of the process chamber, thereby leading to further temperature non-uniformities which can cause thermal stress, substrate warpage, defects, dislocations, litho-overlay errors, and slip.
Thus, the inventors have provided an improved apparatus for processing a substrate.